South Africa, the most obese country in sub-Saharan Africa, could reduce the number of its overweight citizens by 220 000 should it institute a 20% tax on sugar-sweetened beverages. This is according to new research in the peer-reviewed journal Plos One published by the Public Library of Science on Tuesday.

The study, which used a number of population-based studies and mathematical modelling to predict the effect that a 20% tax on sugar-sweetened drinks would have on the population, found that this intervention would result in a 3.8% reduction in obesity for men and a 2.4% reduction for women.

A study published in the Lancet this year found that 70% of the South African population is overweight or obese.

Previous research has shown that consumption of these beverages can lead to weight gain in adults and children. Being obese predisposes a person to a number of diseases including heart disease, diabetes, cancer, hypertension, stroke and osteoarthritis, according to the Center for Disease Control and Prevention in the United States.

“While [sugar-sweetened beverages] alone may not be the only reason for an increase in body fat, these fizzy drinks do not contain any essential nutrients, have a high sugar content and a strong link to weight gain. Drinking just one a day increases the likelihood of being overweight by 27% for adults and 55% for children,” said senior researcher for the study Karen Hofman in a press release.

Each 330ml serving of a fizzy sweetened drink contains an average of eight teaspoons of sugar; the same size sweetened fruit juice contains nine, according to the researchers.

The National Strategic Plan for the Prevention and Control of Non-Communicable Diseases, published by the health department last year, suggests taxes should be placed on certain unhealthy foods including those high in sugar.

“Dietary changes that are needed in South Africa include … decreased use and intake of sweetened [sugary] foods and drinks.”

Said Hofman: “There aren’t any taxes on unhealthy foods in South Africa as yet.”

The health department’s plan further states that, globally, 5% of all deaths are related to obesity.

With 42% of South African women classified as overweight or obese, the researchers believe that it is the responsibility of the government to keep people healthy, and one way to do this is by “nudging” consumers to make healthier choices.

Amy Green is a health reporter at the M&G's health journalism centre, Bhekisisa.